Known internal combustion engines include an oil pump for a lubrication system located in a casing member covering a first end of a crankshaft. A water pump for a water cooling system is provided on a second end of the crankshaft. A drive shaft of the oil pump is connected coaxially with a first end of a balancer shaft rotatably installed on the crankcase and extending parallel to the crankshaft. A water pump drive shaft is connected coaxially with a second end of the balancer shaft.
Placing the oil pump and the water pump on opposite ends of the crankcase in the crankshaft direction (i.e., axial direction) in this manner requires a separate and individual casing member. This increases the number of components and leads to a desire to further improve assembly and maintainability.